#!/usr/bin/python
# -*- coding: utf8

__author__ = 'daddy-bear'


def __tadpole(graph):
    externalEdges = graph.edges(graph.externalVertex)
    if len(externalEdges) != 2:
        return None
    if externalEdges[1].internal_nodes[0] == externalEdges[0].internal_nodes[0]:
        return ("0", (0, 0))
    return None